Note: Descriptions are shown in the official language in which they were submitted.
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Pump Apparatus
The present invention relates to a pump apparatus, in particular to a positive
displacement pump
apparatus.
Pumps for pumping relatively viscous liquids tend to require multiple bearings
and dynamic seals
for the drive shaft of the pump. These can wear relatively quickly, typically
requiring the pump to
be replaced. In addition, these additional components add to the complexity
and cost of the
pump.
It is desired to provide a pump which has a simpler design that requires fewer
components.
According to a first aspect of the invention, there is provided a pump
apparatus comprising a
pump chamber having a fluid inlet and a fluid outlet; and a flexible impeller
mounted for rotation
within the pump chamber, wherein the pump chamber is defined by a curved wall,
the wall
including a first wall portion having a first radius and a second wall portion
having a second
radius, wherein the second radius is greater than the first radius; the
flexible impeller includes a
plurality of radially extending vanes, wherein the vanes contact the curved
wall of the pump
chamber such that separate pump cavities are defined between adjacent vanes
and the pump
chamber wall; the flexible impeller is driven to rotate by a drive shaft; the
drive shaft passes
through a first end wall which closes one side of the pump chamber and a
distal end of the drive
shaft rotates within a bearing defined by a second end wall which closes the
opposite side of the
pump chamber; and wherein the fluid inlet and the fluid outlet are defined in
the second end
wall.
The skilled person will appreciate that the pump is based on a known flexible
impeller pump in
which a number of flexible pump cavities are defined between adjacent vanes
and the pump
chamber wall. The volume of the pump cavities decreases as the impeller moves
from the first
wall portion to the second wall portion, which in turn forces the fluid
located within the pump
cavity out of the cavity and through the fluid outlet.
The term "flexible" refers to the radially extending vanes which are deflected
by contact with wall
of the pump chamber. The radially extending vanes may be resiliently
deformable.
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By defining the fluid inlet port and the fluid outlet port in the second end
wall, the curved wall of
the pump chamber can be formed as a continuous, uninterrupted surface. This
further allows the
curved wall of the pump chamber to be formed from a separate sleeve. Thus, the
second end wall
defines a fluid inlet port, a fluid outlet port and the bearing portion which
is configured to receive
the distal end of the drive shaft.
Suitably, the centre point of the first wall portion radius is co-axially
aligned with the centre of the
pump chamber and the drive shaft for the flexible impeller. However, the
centre point for the
second wall portion radius may be spaced from the centre point of the first
wall portion and may
even lie outside of the pump chamber. In this way, the second wall portion is
effectively a
flattened portion of the curved pump chamber wall which reduces the volume of
the pump
cavities as they rotate against the second wall portion.
The bearing defined by the second end wall is suitably a closed bearing. In
other words, the
bearing may define a cylindrical aperture which is open at one end to receive
the distal end of the
drive shaft and is closed at its opposite end. In this way, the drive shaft
does not extend through
the second end wall. Such an arrangement avoids the need for a seal to be
provided within the
bearing, as no liquid can leak from the bearing. Additionally, a closed
bearing may further
function as a thrust bearing, which prevents or limits axial motion of the
drive shaft.
The drive shaft for such pumps typically requires one or more bearings and
dynamic seals at its
proximal end and the distal end of the drive shaft is arranged to be free-
floating. However, it has
been found that by forming a bearing in the second end wall (i.e. at the
distal end of the drive
shaft), the shaft only requires a single bearing arrangement and seal at its
proximal end.
The second end wall may be formed from a bearing material such that the distal
end of the drive
shaft is able to rotate within the bearing portion without the need for any
further bearing
components. This is advantageous when pumping food products, as the absence of
bearing
components makes the cleaning of pump apparatus easier. The second end wall is
suitably
.. formed from a polymeric material that is capable of functioning as a
bearing material, such as for
example, PTFE.
For ease of manufacture, the curved wall of the pump chamber may be formed
from a sleeve. In
this way, the sleeve may simply be replaced in the event that it becomes worn
or if different
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pumping characteristics are required. The sleeve suitably fits within a pump
body in use. Thus, the
sleeve may comprise an outer wall having a circular cross section and the pump
body may define
an inner wall having a circular cross section, wherein the diameter of the
outer wall of the sleeve
is substantially the same as the diameter of the inner wall defined by the
pump body.
As noted above, the formation of the inlet port and the outlet port in the
second end wall permits
the use of a sleeve to define the curved wall of the pump chamber.
In embodiments in which the sleeve is formed from a relatively soft material,
it may not be
necessary to include any sealing elements between the sleeve and the pump body
and/or the end
walls of the pump apparatus. This is useful in embodiments in which the pump
is used to pump
food products and it is necessary to thoroughly clean the pump from time to
time, as the absence
of sealing elements avoids or minimises locations in which bacteria can build
up.
However, in embodiments in which the liquid to be pumped is relatively
viscous, the impeller may
be formed from a stiffer material and sleeve may also be formed from a stiffer
material. In such
embodiments, it may be necessary to include one or more sealing elements
between the sleeve
and the end walls of the pump apparatus.
Pumps according to the invention are driven by motors, typically electric
motors, and it is often
desired to couple the pump directly to a motor (e.g. an electric motor). In
such embodiments, the
pump apparatus further includes a connector which connects the pump apparatus
to a motor.
The connector suitably also defines the first end wall. In this way, a minimum
number of
components are required. Thus, the drive shaft passes through the first end
wall and into a cavity
defined by the connector. The proximal end of the drive shaft may be coupled
with an output
shaft from the motor within the cavity defined by the connector. In
embodiments in which the
proximal end of the drive shaft is coupled to the output shaft from the motor,
the proximal end of
the drive shaft may include a first part of a two part coupling. A second part
of the two part
coupling is suitably carried by the output shaft of the motor.
According to a second aspect of the invention, there is provided a combination
of a pump
apparatus according to the first aspect of the invention as defined herein and
an electric motor,
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wherein a rotary drive output from the electric motor is coupled to the drive
shaft of the pump
apparatus.
In an embodiment of the invention, one of the output shaft from the electric
motor and the drive
shaft of the pump apparatus includes a first part of a two-part connector and
the other of the
output shaft from the electric motor and the drive shaft of the pump apparatus
includes a second
part of the two-part connector.
In order to make the coupling of the two parts of the two-part connector
easier, the two-part
connector is suitably self-aligning. For example, the first part of the two-
part connector may
include a rib and the second part of the two-part connector may include a
channel having sloped
sides, such that the sides of the channel guide the rib into the channel. In a
further embodiment,
the two-part connector may include more than one rib and a corresponding
number of channels.
For example, the two-part connector may include three ribs and three channels
having sloped
sides. The channels may be arranged radially about a central axis. In this
way, the angular
orientation of the ribs relative to the channels does not matter, as the
sloping sides of the
channels will cause the shaft which carries the ribs to rotate until the ribs
are aligned with the
channels and the first part of the two-part connector is coupled to the second
part of the two-
part connector.
The pump apparatus of the second aspect of the invention is operatively
coupled to an electric
motor. The pump apparatus may be connected directly to the electric motor, for
example via a
connector which forms part of the pump apparatus, wherein the electric motor
is secured to the
connector; or the pump apparatus may be indirectly connected to the electric
motor. In such
embodiments, the pump apparatus may be connected to the electric motor via one
or more
intermediate components. Thus, the pump apparatus and the electric motor may
form a single
unit or the pump apparatus may be operatively connected to, but spaced from
the electric motor.
According to a third aspect of the invention, there is provided a pump
apparatus including a
pump body and a pump receiver configured to receive the pump body, wherein the
pump body
defines a pump chamber having a fluid inlet and a fluid outlet; a pump element
which urges the
fluid to flow from the inlet to the outlet; and at least one permanent magnet;
wherein the pump
receiver includes at least one permanent magnet; and wherein the pump body has
a first
orientation relative to the pump receiver in which the magnets are aligned and
pump body is
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coupled to the receiver via an attractive magnetic force, and a second
orientation relative to the
pump receiver in which the magnets are out of alignment and the pump body is
detachable from
the pump receiver.
The pump body of the third aspect of the invention is secured to a pump
receiver via a magnetic
attraction. When the magnets are aligned, the pump body is securely fixed to
the pump receiver.
However, it can readily be removed from the pump receiver simply by moving the
pump body
and/or the pump receiver such that the pump body is in its second orientation
relative to the
pump receiver and the magnets are out of alignment. This is useful in cases in
which the pump
body needs to be removed periodically for cleaning or replacement.
The pump receiver may form part of a motor, such as an electric motor, or it
may form an
intermediate component between the pump body and the motor.
The pump body of the third aspect of the invention may be any positive
displacement pump
apparatus. However, in an embodiment of the invention, the pump body of the
third aspect of
the invention comprises a pump apparatus according to the first aspect of the
invention (i.e. a
flexible impeller pump). Thus, the pump apparatus of the first aspect of the
invention may include
at least one permanent magnet. In such embodiments, the pump body of the third
aspect of the
invention may include any of the features as defined and described herein in
connection with the
first aspect of the invention.
According to an embodiment of the invention, the pump receiver includes two
spaced apart
permanent magnets, wherein in the first orientation, the pump body magnet is
aligned with a
first one of the pump receiver magnets, the poles are opposite and an
attractive force is
generated between the magnets; and in the second orientation, the pump body
magnet is
aligned with a second one of the pump receiver magnets, the poles are the same
and a repulsive
force is generated between the magnets which urges the pump body away from the
pump
receiver.
Alternatively, the pump body may include two spaced apart permanent magnets,
wherein in the
first orientation, the pump receiver magnet is aligned with a first one of the
pump body magnets,
the poles are opposite and an attractive force is generated between the
magnets; and in the
second orientation, the pump receiver magnet is aligned with a second one of
the pump body
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magnets, the poles are the same and a repulsive force is generated between the
magnets which
urges the pump body away from the pump receiver.
In both of the embodiments defined above, the pump receiver magnet(s) may be
carried by a
rotatable collar which can be rotated between the first and second
orientations. Alternatively, the
pump body may be rotatable relative to the pump receiver between the first and
second
orientations.
In a further embodiment, the pump body includes a pair of spaced apart body
magnets
(permanent magnets) and the pump receiver includes a pair of spaced apart
receiver magnets,
wherein in the first orientation, the pair of spaced apart body magnets are
aligned with the
spaced apart receiver magnets and there is an attractive magnetic force
between each pair of
magnets, and in the second orientation, one of the body magnets is aligned
with one of the
receiver magnets, the other of the body magnets is out of alignment with the
other of the other
of the receiver magnets, and there is a repulsive magnetic force between the
aligned magnets.
The skilled person will appreciate that the features described and defined in
connection with the
aspects of the invention and the embodiments thereof may be combined in any
combination,
regardless of whether the specific combination is expressly mentioned herein.
Thus,
combinations of optional features described and discussed herein are within
the scope of the
invention.
An embodiment of the invention will now be described, by way of example only,
with reference
to the accompanying drawings in which:
Figure 1 is an exploded perspective view of a combination of a pump apparatus
according
to the first aspect of the invention with an electric motor;
Figure 2 is a sectional view through the combination shown in Figure 1 in its
assembled
configuration;
Figure 3 is an exploded perspective view of a pump body according to the third
aspect of
the invention; and
Figure 4 is an exploded perspective view of a pump receiver according to the
third aspect
of the invention.
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For the avoidance of doubt, the skilled person will appreciate that in this
specification, the terms
"up", "down", "front", "rear", "upper", "lower", "width", "above", "below",
etc. refer to the
orientation of the components of the invention when installed for normal use
as shown in the
Figures.
Figure 1 shows a combination 2 of a pump apparatus 4 and an electric motor 6.
The pump
apparatus 4 includes a pump body 8 within which is located a sleeve 10 that
defines a pump
chamber. 0-ring seals 12, 14 provide a fluid tight seal between the sleeve 10
and end walls of the
pump apparatus 4 (discussed below).
A flexible impeller 16 is located within the sleeve 10. The flexible impeller
16 includes eight
flexible vanes 18, the ends of which wipe against the inwardly facing wall of
the sleeve 10 in use.
Such an arrangement defines eight pump cavities within the pump chamber,
wherein each pump
cavity is defined by an adjacent pair of the vanes 18 and the inwardly facing
wall of the sleeve 10.
The flexible impeller 16 includes an insert element (not shown) at its core
which defines a
hexagonal shaped central channel. A drive shaft 20, which has a corresponding
hexagonal shaped
portion is located within the central channel, such that the flexible impeller
16 is rotationally
locked to the drive shaft 20.
While the outwardly facing wall of the sleeve 10 has a circular cross-
sectional shape, the inwardly
facing wall has a first portion which has a first radius and a second portion
which has a second,
greater radius. This has the effect of providing the inwardly facing wall with
a "flattened" portion
(i.e. the second portion). As the flexible impeller 16 is driven to rotate by
the drive shaft 20, the
volume of the pump cavities decrease as they pass the "flattened" portion of
the sleeve 10 (i.e.
the second portion of the inwardly facing wall of the sleeve). This decrease
in pump cavity volume
forces the fluid from the pump cavities.
The pump chamber defined by the sleeve 10 is closed at one end by an end plate
22. The end
plate defines a fluid inlet port 24 which is aligned with the first portion of
the sleeve 10 and a fluid
outlet port 26 which is aligned with the second portion of the sleeve 10.
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The end plate 22 further defines a bearing portion 28, which is shown in more
detail in Figure 2. A
distal end 30 of the drive shaft 20 is located within the bearing portion 28
and is rotatably
supported by the bearing portion 28.
The opposite end of the pump chamber is closed by a closure portion 34 of a
connector element
36. The connector element defines therein a cavity 38 and includes a mating
surface 40, opposite
to the closure portion 34, which permits the mating of the connector element
36 to the electric
motor 6.
The drive shaft 20 extends through a channel 42 defined through the closure
portion 34 of the
connector element 36 and a proximal end 32 of the drive shaft 20 terminates in
the cavity 38
defined by the connector element 36. A dynamic seal 44 and a support bearing
46 are coupled to
the proximal portion 32 of the drive shaft 20. The dynamic seal 44 prevents
fluid from within the
pump chamber leaking through the closure portion 34 and the support bearing 46
supports the
.. proximal end 32 of the drive shaft as it is rotated by the electric motor
6.
A first part 48 of a two-part connector is secured to the proximal end 32 of
the drive shaft 20. The
first part 48 of the two-part connector is engaged by a second part 50 of the
two-part connector
which is carried by an output shaft 52 of the electric motor 6.
Figure 3 shows a flexible impeller pump 104 which is similar to that described
above in
connection with Figures 1 and 2.
The pump 104 includes a pump body 108 within which is located a sleeve 110.
The sleeve 110 has
the same physical features as the sleeve 10 described above, but is formed
from PTFE, which is a
softer material, and as such, the pump 104 does not require 0-ring seals to
prevent fluid from
within the pump chamber defined by the sleeve 110 leaking between the sleeve
110 and end
plates 122, 134. A fluid-tight seal is formed between the sleeve 110 and the
end plates 122, 134.
A flexible impeller 116, which is identical to the flexible impeller 16
described above, is located
within the sleeve 110 and the flexible impeller is driven to rotate by a drive
shaft 120 which is
similar to the drive shaft 20 described above.
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One end of the pump chamber defined by the sleeve 110 is closed by the end
plate 122. Again,
the end plate 122 is identical to the end plate 22 described above and it
includes a fluid inlet port
124, a fluid outlet port 126 and a bearing portion (not shown in Figure 3)
which is shaped and
configured to rotationally support a distal end 130 of the drive shaft 120.
A proximal end 132 of the drive shaft 120 also includes a dynamic seal 144 and
a support bearing
146.
The pump 104 differs from that shown in Figures 1 and 2 in that the pump body
108 includes an
alignment tab 160 and that the opposite end of the pump chamber is closed by
the second end
plate 134.
The drive shaft 120 passes through a channel 142 defined by the second end
plate 134. In this
embodiment, the support bearing 146 is located within the channel 142.
The proximal end 132 of the drive shaft 120 carries a first part 148 of a two
part connector, which
is discussed in more detail below.
On the opposite side of the second end plate (i.e. facing away from the pump
chamber) is carried
a first array of four permanent neodymium magnets 162.
Figure 4 shows a pump receiver 202 for magnetically receiving the pump 104
shown in Figure 3.
The pump receiver 202 comprises a mounting plate 204 to which is fixed a
bearing plate 206 and
a pump receiving element 208.
The bearing plate 206 defines therethrough a channel within which is located a
pair of support
bearings 210a, 210b which rotationally support an auxiliary drive shaft 212.
The auxiliary drive
shaft passes through the channel defined by the bearing plate 206 and carries
at its first end a
second part 214 of the two-part connector which is spaced from the bearing
plate by a cylindrical
spacer 216.
The first part 148 of the two-part connector includes three radial ribs
arranged about a central
axis. The ribs include sloped sides. The second part 214 of the two-part
connector defines three
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channels which correspond to the ribs of the first part 148 and which also
include sloped sides.
The arrangement of the first and second parts 148, 214 of the two-part
connector results in a self-
aligning connector, as the ribs will align themselves with the corresponding
channels as the first
part 148 is moved towards the second part 214. The drive shaft 120 will be
urged to rotate by the
engagement of the sloped sides of the ribs with the sloped sides of the
channels until the ribs are
aligned perfectly with the corresponding channels.
At its second end, the auxiliary drive shaft 212 carries a drive input
connector 218 which may be
connected to an output shaft of an electric motor (not shown).
Located between the bearing plate 206 and the pump receiving element 208 is a
rotatable collar
220 which is rotatably coupled to the pump receiving element 208 such that it
can rotate through
an arc defined between stops (not shown). A first stop defines a first angular
orientation of the
rotatable collar 220 and a second stop defined a second angular orientation of
the rotatable
collar. The rotatable collar 220 further includes a manually operable tab 221.
Sandwiched between the rotatable collar 220 and a securing ring 222 is a
second array of four
permanent neodymium magnets 224.
The pump receiving element 208 includes a cylindrical body portion 226 which
is open at one end
to define an aperture which is configured to receive therein the pump body
108. The cylindrical
body portion 226 defines therein a locating slot 228 which is sized and
configured to receive
therein the alignment tab 160 of the pump body 108. This ensures that the pump
body 108 has a
predetermined orientation relative to the pump receiving element 208 when the
pump body is
located within the cylindrical body portion 226.
In use, the rotatable collar 220 is arranged in its first orientation and the
pump body 108 is
located within the cylindrical body portion 226 with the alignment tab 160
located within the
locating slot 228. With the rotatable collar 220 in its first orientation and
the pump body correctly
aligned within the pump receiving element 208, the first array of magnets 162
aligns with the
second array of magnets 224 and a magnetic attraction force is generated
between each of the
magnets 162 and 224. In this arrangement, the removal of the pump 104 from the
receiver 202 is
resisted.
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As the pump 104 is drawn into the receiver 202 by the magnetic attraction, the
first part 148 of
the two-part connector aligns automatically with the second part 214 of the
two-part connector
as discussed above. Thus, the drive shaft 120 is operatively coupled to the
auxiliary drive shaft
212 and the drive shaft 120 may be driven by an electric motor when the
auxiliary drive shaft 212
is coupled to an electric motor.
In order to detach the pump 104 from the receiver 202, the collar 220 is
rotated to its second
orientation via the tab 221. In this orientation, a first pair of the first
magnets 162 are moved
from alignment with a first pair of the second magnets 224 to alignment with a
second pair of the
second magnets 224. This results in the second pair of first magnets 162 and
the first pair of the
second magnets 224 no longer being in alignment with corresponding magnets.
Furthermore, as
the poles of the first pair of first magnets 162 and the second pair of second
magnets are the
same, a magnetic repulsive force urges the pump 104 away from the receiver
202.
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